The use of refrigeration apparatus for cooling at low temperatures is known. As discussed in U.S. Pat. No. 3,636,719, conventional refrigeration apparatus can take on a variety of configurations. In a displacer type unit, a basic design involves the use of a displacer positioned in a cylinder defining expansion and compression chambers. Coupled between these chambers is a regenerator type heat exchanger through which gas passes. In operation, the displacer on which a mechanical reciprocal movement is imparted, reciprocates between upper and lower dead points. At the lower dead point compressed gas is admitted into the compression chamber which is then compressed upon movement of the displacer. The gas then passes through the heat exchanger where the gas exchanges heat with it and into the expansion space where it undergoes adiabatic expansion which decreases its temperature and produces cold. When the displacer moves down, the gas in the expansion chamber is forced through the heat exchanger, giving it cold. The cycle then repeats itself continually producing cold.
While Stirling engines have been utilized in refrigerating applications (see Stirling Engines by G. Walker, Clarendon Press, 1980, Pages 446-450) and have operated satisfactorily, however they are extremely complicated and expensive to construct and have high vibrational levels. Accordingly, there exists a need for a refrigerator apparatus which operates on a Stirling engine cycle which is effective at very low temperatures, providing for good thermodynamic performance and which achieves low overall vibration levels, providing for hydrodynamic gas bearings for long life and has low cryocooler contamination.
It would further be desirable to design the invention so that it minimizes the size of components, and reduces manufacture and assembly costs.